A waste-gas cleaning system for cleaning aerosol-laden gases or atmospheres includes at least one assembly including an ionization section and a collection section provided downstream thereof. The waste-gas cleaning system is connected by its inlet to a raw gas channel or raw gas channels. At its outlet, the waste-gas cleaning system discharges clean gas into the environment or into a waste-gas channel leading further on.
In a space-charge precipitator, unipolar charged particles are precipitated according to the field of their own space charge.
Depending on the structural design of the precipitator, the self-precipitation can occur in a wet scrubber within the tubular electrodes in a filter. Wet scrubbers have provided a useful increase in efficiency by charging the particles/aerosols prior to their entry into the scrubber. Charged particles are precipitated by wet scrubbing and electrostatic precipitation under the influence of the space charge.
An electrostatic precipitator also operates on the principle of mutual repulsion of charged particles at a wall at a reference potential, for example, at ground potential. As the charged particles pass through the grounded section of a precipitator, a fraction of the charged particles are forced to the grounded wall by the electric field created by the space charge. Precipitated particles are entrained in the coalesced water which runs down the walls of the grounded electrode tubes and is drained off.
DE 22 35 531 describes an ionizing wet scrubber in which a gas stream to be processed is ionized before it passes through the wet scrubber so as to provide the particles/aerosols in the gas stream with an electric charge of predetermined polarity. As the gas stream is flowing, the charged particles/aerosols are brought into proximity with the scrubber liquid and/or the packing elements by the attractive forces acting between the charged particles and the electrically neutral packing elements and the liquid. The particles are removed from the gas stream by the scrubber liquid.
US 2006/0236858 A1 describes an ionizing particulate scrubber composed of a charging section and a collection section. The collector includes either a fixed or fluid bed packed section which is constantly irrigated from above. The gas stream and charged particulate are immediately sent from the charge section to the collection section of the system, and clean gas is then passed through an entrainment separator section to remove liquid droplets.
The described separators have a collection chamber disposed between the charging section and the collection section. Therefore, the space charge distribution at the collector inlet is homogeneous. The direction of the gas stream is the same at the inlet and outlet of the collector.
U.S. Pat. No. 4,072,477 or DE 10 2006 055 543 describe electrostatic space-charge precipitators which do not have a collection chamber between the charging section and the collection section. The outlet of the charging section is connected to a chamber containing electrically conductive packing material such as, for example, tower packing elements. The direction of the gas stream is either the same at the inlet and outlet, or the gas stream changes its direction in the collection section. In the latter case, the space charge distribution in the inlet zone of the collector is not homogeneous. It has a maximum in the region where the gas stream enters the collector and has a minimum at the wall opposite the inlet zone. The resulting space charge distribution is not homogeneous. When particles are precipitated, the space charge field decreases, and the aerosol collection efficiency deteriorates in the central region and the region opposite the flow entry. Because of that, the inlet zone of the collector is frequently ineffective for particle collection.
Prior art space-charge precipitators (U.S. Pat. No. 4,072,477, FIG. 1, and DE 10 2006 055 543, FIGS. 13 and 14) are illustrated in FIG. 1 herein for purposes of comparison. In these precipitators, the outlet of the charging/ionization section is coupled to a grounded collection section composed of electrically conductive packing material, such as tower packing elements. The gas stream changes direction in the inlet zone of the collection section.
DE 10 2006 055 543, DE 10 2005 4045 010, DE 10 2005 023 521 and DE 102 44 051 describe circularly curved, grounded nozzle plates.
Describes a charging/ionization section in DE 10 2006 055 543.
DE 102 59 410, describes a collector, and a spray system for washing purposes